AMSA Premed is a group for students run by students in hopes of generating interest in the field of medicine and general health care. It is focused on working towards creating professionalism for those entering into careers of medicine. This organization is international and has chapters for both undergraduates as well as current medical students and is a valuable resource for discovering all of the elements involved in medical education. Visit AMSA's website for more information about becoming a member.
http://www.amsa.org/premed/

Along with creating an inviting atmosphere for beginning premedical students, AMSA offers many benefits to its members. The following link details some of the advantages that come with an AMSA membership. Various venders are represented from hotels, insurance companies, software companies, and everything in between.
http://www.amsa.org/member/benefits.cfm

Make sure to check out the free subscription to The New Physician magazine
http://www.amsa.org/tnp/

Perhaps the most helpful aspect of becoming a member is the availability of various student opportunities. Activities range from leadership roles to scholarships to internships and beyond. Take a look at the list of AMSA-sponsored opportunities below and find something that interests you.
http://www.amsa.org/premed/opps.cfm